Inverter Choice - Remote Display - Sunny Beam or PVI Desktop

[Graddie]

I'm currently choosing a domestic PV system and had a number of installers round. No two people say the same thing so I'm doing a lot of research to try to make up my own mind! I've found Electricians Forum invaluable - thank you.

I think I've settled on 17 x Sanyo N235 panels = 3995 and narrowed down inverter choice to SMA SB4000TL or Aurora PVI 3.6.

Of great importance to me is a remote monitor. The inverter will have to be in the garage, a separate building some 50 mtrs from the house. I'm pretty sure bluetooth to the SMA Sunny Beam won't be up the job, even with a Repeater, which would have to be outside. So I'm leaning towards the Aurora as I understand it has wireless transmission with a range of 300 metres to a PVI Desktop.

However, there is no direct line of sight - house is set back slightly around the bend of a lowish hillside from the garage. We have a phone handset in the garage which picks up calls from the base station in the house but the signal is not great and to talk you have to walk closer to the house.

My questions are:-

1. Has anyone got experience please of the Aurora PVI Desktop? Will it work without a direct sight line from the inverter?

2. I've read that the inverter works better if a little undersized so again the Aurora 3.6 may be better with the 3995 of Sanyo panels. But SMA inverters seem to be much more widely used and recommended and I wonder why?

Any advice very gratefully received.

 

[Worcester]

SMA and Power-One (Aurora) are #1 and #2 respectively in the world for inverters by volume shipped.

We use both and have been very happy with the quality and support of the manufacturers - both have a UK office.

Post the the angle and orientation of the panels here and someone will run it through PV*Sol for you and give you the estimated kWh/annum for both configurations,

 

[BruceB]

The Aurora desktop works on 868MHz. Very much line of sight therefore. The inverter does come with built in RS485, so you can have a wired connection between the inverter and the Aurora desktop display

 

[furrypants]

Getting the Aurora 3600 indoor inverter, do you know if i attach this UPort 1110 - Moxa UPort 1110 1-port RS-232 USB-to-serial adaptor i would be able to download info from the inverter to pc every month?

 

[BruceB]

I had not realised the indoor version had a RS232 connection also, but see it does from the spec sheet. In principle what you suggest should work. but I have not tried it. Personally, I would go for the outdoor version, which is a newer generation of inverter, is slightly more efficient and has a USB output built in, so no need for a converter.
Regards
Bruce

 

[furrypants]

What's the price diference between the two tho?

 

[Graddie]

Post the the angle and orientation of the panels here and someone will run it through PV*Sol for you and give you the estimated kWh/annum for both configurations,

Angle will be 30 and orientation will be 180. Aurora would be the 3.6 outdoor version.

Thank you.

 

[Graddie]

The Aurora desktop works on 868MHz. Very much line of sight therefore. The inverter does come with built in RS485, so you can have a wired connection between the inverter and the Aurora desktop display

We have an unused 6 core telephone wire that we ran underground from the house to the garage when the latter was built. Could we use that for the wired connection?

 

[Worcester]

Maybe!

From the Aurora Manual:
"WARNING: The RS-485 cable must provide at least 600V protection"

RS485 usually uses three conductors, most installation would use either cat5 (ethernet) cable which has 4 twisted pairs, or a cable with two twisted pairs and a shield - the official spec for RS485 useage is either LiYCY, 2x2x0,5mm (n.2 twisted pairs) + shield or RS-485 cable (1pair + 1 conductor) + shield

The specification for the number of twists / m and the number of times the twisted pairs are twisted is what stops the interference on the signal line, you may get away with using one of the twisted pairs in your exiting cable for the signalling and then join the two conductors of another twisted pair together to use as the 'ground' - if the ground is not connected properly at both ends in an RS485 comms system the signal cannot be interpreted.

In the Aurora inveters, usually:
Signal wires must be connected to +T/R and –T/R terminals
Ground wire must be connected to RTN terminal

The normal maximum distance for RS485 comms is 4000ft (1200 m)

Seeing as few computers have an RS485 interface, you'll need an RS232 (that's the good old 9 pin serial port on a computer) to RS485 converter as well.

And then you need the software that will monitor / communicate with the RS232 port.

 

[Graddie]

Thank you for this comprehensive reply. Maybe phone wire won't do the job! Very useful though in helping us focus down on the options.

I'd be very grateful if someone could run two systems through software for me for comparison.

To recap:

30 degree angle and 180 degree orientation.

Sanyo N235 + SB4000TL OR Sanyo N235 + Aurora PVI 3.6 outdoor

 

[BruceB]

Whilst Worcester is correct in what he says, you are only trying to get theRS485 to work over 50m. That is an undemanding distance for it on almost any cable. Other rs485 systems I have used have been happy on burglar alarm wire up to 100mm, which is thin and does not have twisted pairs. You will need to sheath the cable appropriately inside the inverter to get normal data cables up to the 600V insulation level.